The discharge of pollutants into the atmosphere has become of increasing concern as the rate of discharge increases and as the level of pollutants in the atmosphere increases. One of the sources of air pollution is the sulfur oxides and particulate matter which are discharged with the flue gases during the combustion of sulfur-containing fuels. A number of systems have been developed or proposed to remove the sulfur oxides and particulate matter from the flue gases. One of the first commercial systems involves scrubbing the flue gases with an aqueous solution which contains materials which will react with the sulfur oxides. The most commonly used materials are limestone and dolomite which may be added either to the furnace or directly to the scrubbing solution. However, unless specific measures are taken and very careful controls maintained on the system chemistry, sulfur oxide removal will not be maximized and precipitates can form in the scrubber and the system piping which tend to plug up the system and may eventually force shutdown.